Zetsu could be a mysterious informant in a Naruto fanfic. He could be lurking in the shadows, gathering information for either the good guys or the bad guys and providing crucial intelligence that changes the course of events in the story.
Well, one way could be in their physical abilities. Maybe in the fanfic, Naruto is shown to have some of Zetsu's stealthy movement skills, like being able to blend into the environment in a similar way. Another similarity could be in their connection to nature. Zetsu has a strong link to the plant - like aspects of nature, and Naruto's chakra might be shown to have a similar kind of connection in the fanfic.
In some fanfics, Naruto might have Zetsu's ability to blend into the environment or be as stealthy as him.
In a fanfic where Naruto is trained by Zetsu, the story could take an interesting turn. Zetsu has knowledge of the Akatsuki and their secrets. Naruto could learn about the organization from the inside out. This knowledge could help him in his quest to bring peace. He might also gain some physical enhancements. Zetsu is quite durable in his own way, and Naruto could inherit some of that sturdiness. This would make him an even more formidable opponent in battles against strong foes like Pain or Madara.
The fanfic might explore new aspects of Naruto's character by comparing him to Zetsu. It could show different sides of Naruto that we haven't seen before, like his more devious or strategic side if he takes on some of Zetsu's traits. This exploration of character depth can be really engaging for readers.
Naruto could be the fearless field agent, always ready to jump into action and take on any danger head - on. Hinata might be the intelligence analyst, using her Byakugan to carefully observe and analyze all the information they gather.
He could be a valiant knight. Picture him in shining armor, riding a white horse and coming to the rescue in battles. Maybe he's a knight loyal to House Stark and helps them in their fight against the Lannisters.
They could be antagonists. Maybe they are a family of dark wizards who oppose Harry and his friends. They could try to steal the Philosopher's Stone or disrupt the Triwizard Tournament.
Perhaps Naruto controls Zetsu to help him in battles. Zetsu could act as a distraction while Naruto sets up his more powerful jutsu. For example, Zetsu could split into multiple forms and confuse the opponents, giving Naruto an opening to attack.
One common role is that of a Pokemon trainer. They travel around, compete in gym battles, and aim to become a Pokemon master.
Zetsu's ability to split into two parts can be used to create interesting plot devices. For example, one part of Zetsu could be captured by the protagonists, while the other part goes on to execute a different part of the villain's plan.